Finding out you are pregnant is one of life’s most exciting moments. But one of the first questions every expectant mother asks is — when is my baby due? Here is everything you need to know about calculating your pregnancy due date accurately.
What is a Due Date? A due date — also called an Estimated Due Date (EDD) — is the date your baby is expected to be born. Most pregnancies last around 40 weeks from the first day of your last menstrual period (LMP).
How is a Due Date Calculated? The most common method is Naegele’s Rule:
- Take the first day of your last menstrual period
- Add 1 year
- Subtract 3 months
- Add 7 days
For example, if your LMP was January 1, 2025 — your due date would be October 8, 2025.
Using Our Due Date Calculator Our Due Date Calculator does all this instantly. Simply enter the first day of your last period and it will give you your estimated due date, how many weeks pregnant you are and your trimester breakdown.
Is the Due Date Always Accurate? Not always. Only about 5% of babies are born exactly on their due date. Most babies arrive within 2 weeks before or after. Your doctor will also use an ultrasound scan to confirm your due date.
What If I Don’t Know My LMP? If you are unsure of your last period, an early ultrasound scan is the most accurate way to estimate your due date. Your healthcare provider can help with this.
Conclusion: Your due date is an important milestone but remember it is an estimate. Use our Pregnancy Calculator and Due Date Calculator to stay on track and always consult your doctor for personalised medical advice.